Comparison of different Tele-(Zoom)-Lenses for Canon EF and AF Microadjustment

For photographers telephoto lenses with a very good optical quality are quite important, especially when wildlife is the preferred motive, as smallest details have to be resolved and in image processing digital zooming is used. But also for astrophotography a telephoto lens with a good image quality is essential, too, as imaging stars is the killer application for every optics. Any optical abberation across the whole field will be easily visible.

I have compared the following Canon EF optics:

1. EF 70-200 f4 L IS USM
2. EF 100-400 L IS USM
3. EF 500 f4 L IS USM

I used a test chart and made test shots with every optic on my Canon 1D Mark III. I changed the distance of the lens to the test chart to have the same same imaging scale for each lens and focal length.

AF Microadjustment (AF Feinabstimmung)

In order to have the optimum image quality you have to consider, that each lens in combination with a specific camera may have a small front or back focus. In former times this backfocus had to be adjusted by the Canon service. But nowadays Canon added a custom function in the 1D Mark III and all newer cameras that allows you to adjust the backfocus for ever lens seperately. That has to be done before you compare the sharpness of the lenses. I used the test chart and focused it using the autofocus. Then I switched to live view and tried to see if manual focus leads to a better image quality. Conecting your camera to a Laptop and using canons EOS-Utiliy makes that task very easy and comfortable. By changing the AF Microadjustment in small steps I figured out the best adjustment value for every lens. For a zoom lens it is best practice to use a focal length in the middle of the zoom range to adjust the backfocus. Here are the results. Please consider that the differences between values from 0...5 are very very small an hardly visible in tandard daylight shots.

 

 

 

Somehow I don't understand why the EF 100-400 with the Kenko 1,4x reducer has a pretty large backfocus and without the converter a pretty small one, but the EF 500 with/without reducer shows barely no difference. The bad sharpness of the EF 100-400 with teleconverter makes it more difficult to find the right AF adjustment setting, so it might be that the value could be a bit smaller than +8 without loosing sharpness.

But anyhow, by using the AF Microadjustment I get the best sharpness results for each optics.

 

Sharpness comparison

After AF Microadjustment I now compared the different optics with each other qualitatively regarding central sharpness and contrast quality. (There are some sites on the Web with detailed evaluation for many lenses with tons of information, tests and charts. In this short evaluation I will not go that deep. Do a google search for "photozone" or "traumflieger")

1. EF 70-200 f4 IS vs EF 100-400 @ 200 mm





(click onto the image for a larger view)

The Sharpness of the EF 70-200 f4 IS is extremely good compared to the EF 100-400, which of couse covers a larger focal range. The difference seen on this test chart photograph may not be that big, but if you shoot structures like distant trees, or feather of a bird the differences in sharpness will be visible, provided that you zoom in digitally or make a large format print out.

 

2. EF 500 f4 IS vs EF 100-400 @ 400 mm





(click onto the image for a larger view)

Here I have compared the relatively compact EF 100-400 zomm at 400 mm focal length with the heavy Ef 500 f4 IS professional telephoto lens. I have adjusted the distance for the EF 500 to have the same field of view onto the test chart. At 400 mm the EF 100-400 is pretty good, but the sharpness of the EF 500 is better than everything else I have seen up to now.

 

3. EF 500 f4 IS vs EF 100-400 + 1,4x Kenko Telephoto Pro @ 500 mm





(click onto the image for a larger view)

Regarding sharpness the EF 100-400 with the Kenko 1,4x teleconverter at 500 mm focal length and f-stop f7 has no chance against the EF 500. And that is exactly the strength of the EF 500. Pristine sharpness and a very good f-stop at long focal length. Nevertheless the EF 100-400 with the teleconverter is flexible and compared to the EF 500 small and leightweight.

 

4. EF 500 f4 IS vs EF 70-200 f4 IS

(click onto the image for a larger view)

Althought these two lenses differ in focal length significantly a comparison shows, that the EF 70-200 is pretty good at 200 mm compared to the EF 500 reference level lens.